British Standard Whitworth
British Standard Whitworth (BSW) is an screw thread standard that uses inches. It was created in 1841 by British engineer Joseph Whitworth and became the world’s first national screw thread standard. The 55-degree thread angle and a specific thread shape were standardized so parts could be made to fit consistently.
BSW spread quickly across the United Kingdom and its former colonies and helped shape manufacturing for bolts, nuts, and many fittings. It also led to related British standards such as British Standard Fine (BSF), British Standard Pipe (BSP), British Standard Conduit (BSCon), and British Standard Copper (BSCopper) threads. The standard aided mass production and accurate, interchangeable parts, a fact shown by its use in ships and gunboats in the Crimean War.
Today, metric threads have largely taken over in modern engineering, but BSW is still found in restoration work, vintage machinery, and some legacy industries. Its influence remains in older equipment and in certain pipe and other fittings that still use Whitworth-style threads.
This page was last edited on 3 February 2026, at 05:01 (CET).